Artificial leg



30, 1936.- T. o. CARROLL ARTIFICIAL LEG Filed March 31, 1935 9 I Hi n TERRY U. CARROLL Patented June 30, 1936 PATENT OFFIQE ARTIFICIAL LEG Terry 0. Carroll, Lakeland, Fla., assignor of onefourth to D. E. Dunbar, Lakeland, Fla.

Application March 31, 1933, Serial No. 663,812

3 Claims.

This invention relates to artificial legs and particularly to that type of leg for use in connection with an amputation above the knee.

One of the objects of the invention is to provide a leg in which the center of gravity of the lower or shin portion is adjustably shiftable laterally with respect to a plumb line passing through the axis of the knee bolt whereby the character of the stride may be improved and made to correspond with that of the sound leg.

Another object of the invention is to provide an eccentric bearing for the knee joint adjustable as to throw so that the axis of oscillation can be shifted laterally or up and down, for the above stated and other purposes.

Other objects of the invention will appear as the following description of a preferred and practical embodiment thereof proceeds.

In the accompanying drawing which forms a part of the following specification, and throughout the several figures of which the same characters of reference have been employed to denote identical parts:

Figure 1 is a view in elevation of the knee joint of a leg embodying the principles of my invention;

Figure 2 is a section taken along the line 2-2 of Figure 1;

Figure 3 is a section taken along the line 33 of Figure 2;

Figure 4 is a section taken along the line 44 of Figure 2;

Figure 5 is a view in perspective of the roller.

Referring now in detail to the several figures,

the numeral I represents the thigh portion of the artificial leg connected to the shin portion 2 by a knee bolt 3. The knee bolt may be of conventional construction and is non-rotatably fixed by means of threads 4 into eyes 5 at the top of the eye plates 6, the latter being secured in any suitable manner as by the rivets l to the thigh portion. A lever 8 is fixed to the knee bolt 3 in known manner and the suspender or shoulder strap 9 passes around a roller I0 mounted in a bifurcation at the front of the lever 8. The function of the shoulder strap is to hold the thigh portion upon the stump as well as to give the shin portion 2 an initial forward impulse when the thigh is lifted.

50 It is customary to mount the thigh portion l directly upon the knee bolt 3, but such construction allows of no adjustment and the stride which such an articulation permits is subject to some defects. In the first place, the nature of the 55 stride cannot be modified and therefore, it cannot be made to correspond to little peculiarities in the natural stride of the sound leg. Furthermore, when the thigh portion is raised in the act of stepping, the shin portion gravitates slowly to its forward'repose position producing a drag of the foot upon the ground to avoid which the wearer accustoms himself to a swaying stride in order that the artificial leg shall clear the ground.

Another defect of the conventional articulation 10 is that when the wearer of the leg starts to place his weight upon it, there is some chance of it buckling and causing him to fall.

The present invention provides an improvement over the conventional joint, by mounting a 15 pair of bearing discs l0 and l I eccentrically upon the knee bolt near the opposite ends thereof, and journalling the thigh portion upon these discs. The eccentric discs l0 and II are displaceable about the axis of the knee bolt and securable in 20 any desired position of adjustment by means such as a series of holes I2 formed in the eccentric and a set screw 13 passing through a threaded aperture in the plate 6 and into one of the holes l2. Through the adjustment thus provided, the knee 25 bolt is shifted forward or backward. The thigh portion i is provided with suitable bearing apertures encompassing the discs l0 and H and suitably lined as with leather as indicated at l 4.

It is assumed that in the leg as normally articu- 3O lated, the center of gravity of the thigh portion lies in a plumb line passing through the axis of the knee bolt. By means of the present invention, the throw of the eccentric may be adjustable forwardly as indicated in Fig. 1 so that the 35 center of gravity of the thigh portion, which passes through the center of the eccentric is shifted forwardly of the plumb line through the knee bolt, as indicated at l5 in Figure 1. When the weight of the wearer is upon the leg, it is 40 obvious that the center of gravity of the thigh portion being forward of the center of gravity of the shin portion which is in the said plumb line, will prevent the leg from buckling into a flexed position.

Furthermore, the relative forward and backward adjustment of the knee bolt also moves the lever 8 and roller H) which is engaged by the shoulder strap forward or backward, permitting the shoulder strap to pick up the shin portion 2 a trifle sooner or later with respect to the lifting of the thigh so that an adjustment can be effected that will prevent the toe dragging, and permit the artificial member to move through an arc directly beneath the body, and eliminating the side swing so common in walking when an artificial leg is employed.

One of the principal features of the invention is that the eccentric discs can be adjusted so as to cause the locomotion of the artificial limb to simulate very closely the natural motion of the sound limb.

It will be observed that with the construction of the present invention, all the parts are substantially flush with the leg portions with which they engage and there are no projecting parts to catch and tear the clothing of the person wearing the artificial leg.

It is also obvious that the eccentric discs may be adjusted at will without the necessity of disassembling the leg or of removing the clothing.

While I have in the above description disclosed what I believe to be a preferred and practical form of the invention, it is to be understood that the details of construction as herein shown and described are merely by way of limitation and not to be construed as restricting the scope of the invention as claimed.

What I claim is:

l. Artificial leg comprising thigh and shin portions, a knee bolt pivotally connecting said portions, said knee bolt being provided with eccentric portions, said thigh portion being journalled upon said eccentric portions, the latter being adjustably displaceable for shifting the knee bolt laterally, a lever fixed to said knee bolt extending radially forwardly thereof, and a shoulder strap roller at the end of said lever.

2. Artificial leg comprising thigh and shin portions, a knee bolt pivotally connecting said portions, and non-rotatably mounted in said shin portion, a lever fixed to said knee bolt and extending forwardly, a suspender associated with the forward end of said lever, bearing disks eccentrically mounted on said knee bolt, a thigh portion journalled on said eccentrically mounted disks, and means for adjustably displacing said disks for shifting the knee bolt and lever laterally.

3. Artificial leg as claimed in claim 2, the adjusting means comprising a series of holes in said discs, an aperture in said thigh portion with which said series of holes are selectively registrable and a set screw passing through said aperture and a selected one of said holes.

TERRY O. CARROLL. 

